Fractal-Percolation Structure Architectonics in Sol-Gel Synthesis.

Irina Kononova,Vyacheslav Moshnikov,Sergey Ignat'Ev,Pavel Kononov

doi:10.3390/ijms221910521

Irina Kononova, Vyacheslav Moshnikov + Show 2 more

Open Access

https://doi.org/10.3390/ijms221910521

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Abstract

It was developed a new technique to assess micro- and mesopores with sizes below a few nanometers. The porous materials with hierarchical fractal-percolation structure were obtained with the sol-gel method. The tetraethoxysilane hydrolysis and polycondensation reactions were performed in the presence of salts as the sources of metal oxides. The porous materials were obtained under spinodal decomposition conditions during application of the polymer sol to the substrate surface and thermal treatment of the structures. The model is based on an enhanced Kepler net of the 4612 type with hexagonal cells filled with a quasi-two-dimensional projection of the Jullien fractal after the 2nd iteration. The materials obtained with the sol-gel method were studied using the atomic force microscopy, electron microscopy, thermal desorption, as well as an AutoCAD 2022 computer simulation of the percolation transition in a two-component system using the proposed multimodal model. Based on the results obtained, a new method was suggested to assess micro- and mesopores with sizes below a few nanometrs, which cannot be analyzed using the atomic force microscopy and electron microscopy.

Highlights

This research focuses on the sol-gel synthesis [31,32] and diagnostics of porous materials with hierarchical fractal-percolation structure as well as the development of a new technique to assess micro- and mesopores with sizes below 10 nm, which cannot be analyzed using the atomic force microscopy (AFM)
It is possible to perform TEOS hydrolysis and polycondensation reactions in the presence of salts as the sources of metal oxides, which significantly expands the possibilities of the method to produce multicomponent silicon dioxide-based oxide materials
With hexagonal cells filled with a quasi-two-dimensional projection of the Jullien fractal after the 2nd iteration chosen in this work is confirmed by the results of etching of porous

Summary

Introduction

Materials with a hierarchical structure [1,2,3], i.e., with a special material (substance) organization in which subunits possessing nano [4,5,6,7]- or microscopic properties are integrated into large-sized associations with a more complex new spatial structure [8,9,10] and functional capabilities, are of great relevance [11,12].Materials obtained with architectonic [1,2,3] synthesis open great opportunities [13,14,15] in energy, environmental protection, bioengineering, catalysis, sensorics, creation of lithiumion batteries, biomedicine, etc [16,17,18,19,20].In [2], some methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro–micropores, micro–mesopores, micro– macropores, meso–mesopores, meso–macropores, multiple porosities: micro–meso– macropores and meso–meso–macropores).It should be noted that according to the IUPAC recommendation three main types of pores are distinguished, i.e., micropores with the sizes below 2 nm, mesopores in the size range from 2 to 50 nm, and macropores with the sizes over 50 nm [21,22]. This research focuses on the sol-gel synthesis [31,32] and diagnostics of porous materials with hierarchical fractal-percolation structure as well as the development of a new technique to assess micro- and mesopores with sizes below 10 nm, which cannot be analyzed using the AFM.

Results

Conclusion